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排序方式: 共有9564条查询结果,搜索用时 984 毫秒
991.
M. Murali Krishna M.S. ShunmugamN. Siva Prasad 《International Journal of Pressure Vessels and Piping》2007
Gaskets play an important role in the sealing performance of bolted flange joints, and their behaviour is complex due to nonlinear material properties combined with permanent deformation. The variation of contact stresses due to the rotation of the flange and the material properties of the gasket play important roles in achieving a leak proof joint. In this paper, a three-dimensional finite element analysis (FEA) of bolted flange joints has been carried out by taking experimentally obtained loading and unloading characteristics of the gaskets. Analysis shows that the distribution of contact stress has a more dominant effect on sealing performance than the limit on flange rotation specified by ASME. 相似文献
992.
Future vehicle applications require the development of reliable and long life batteries operating under high-rate partial-state-of-charge (HRPSoC) working conditions. Work presented in this paper deals with the study of different design parameters, manufacturing process and charging conditions of spiral wound valve-regulated lead-acid (VRLA) batteries, in order to improve their reliability and cycle life for hybrid vehicle applications. 相似文献
993.
Wei-Hsiang Lai Chi-An Hsiao Chien-Hsiung Lee Yau-Pin Chyou Yu-Ching Tsai 《Journal of power sources》2007
Solid oxide fuel cell (SOFC) is characterized in high performance and high temperature exhaust, and it has potential to reach 70% efficiency if combined with gas turbine engine (GT). Because the SOFC is in developing stage, it is too expensive to obtain. This paper proposes a feasibility study by using a burner (Comb A) to simulate the high temperature exhaust gas of SOFC. The second burner (Comb B) is connected downstream of Comb A, and preheated hydrogen is injected to simulate the condition of sequential burner (SeqB). A turbocharger and a water injection system are also integrated in order to simulate the situation of a real SOFC/GT hybrid system. The water injection system is used to simulate the water mist addition at external reformer. 相似文献
994.
This paper presents the experimental results of an actively controlled fuel cell/battery hybrid power source topology that can be widely used in many applications, such as portable electronic devices, communication equipment, spacecraft power systems, and electric vehicles, in which the power demand is impulsive rather than constant. A step-down DC/DC power converter is incorporated to actively control the power flow between the fuel cell and the battery to achieve both high power and high energy densities. The results show that the hybrid power source can achieve much greater specific power and power density than the fuel cell alone. This paper first demonstrates that an actively controlled hybrid with a 35 W hydrogen-fueled polymer electrolyte membrane fuel cell and a lithium-ion battery pack of six cells yielded a peak power of 100 W, about three times as high as the fuel cell alone can supply, while causing a very limited (10%) weight increase to the whole system. After that, another hybrid source using a different battery array (eight cells) was investigated to further validate the control strategy and to show the flexibility and generality of the hybrid source design. The experimental data show that the hybrid source using an eight-cell battery supplied a peak power of 135 W, about four times that of the fuel cell alone. Finally, three power sources including the fuel cell alone and the two hybrids studied were compared in terms of specific power, power density, volume, weight, etc. The design presented here can be scaled to larger or smaller power capacities for a variety of applications. 相似文献
995.
An innovative zero emission hybrid cycle named HICES (hybrid and improved CES cycle) is presented in this paper. It can utilize fossil fuel and low quality thermal energy such as waste heat from industrial processes and solar thermal energy for highly efficient electric power generation. In the HICES cycle, natural gas is internally combusted with pure oxygen. External low quality thermal energy is used to produce saturated steam between 70 and 250 °C as part of the working fluid. The thermodynamic characteristics at design conditions of the HICES cycle are analyzed using the advanced process simulator Aspen Plus. The influences of some key parameters are investigated. The results demonstrate that the thermodynamic performances of the HICES cycle are quite promising. For example, when the external heat produced saturated steam is at 70 °C, the net fuel-to-electricity efficiency is 54.18% even when taking into account both the energy penalties to produce pure oxygen and to liquefy the captured CO2. The incremental low temperature heat to electric efficiency is as high as 14.08% at the same time. When the external heat produced saturated steam is at 250 °C, the net fuel-to-electricity efficiency reaches 62.66%. The incremental low temperature heat to electric efficiency achieves 48.92%. 相似文献
996.
Yong‐Sung Eom Kwang‐Seong Choi Seok‐Hwan Moon Jun‐Hee Park Jong‐Hyun Lee Jong‐Tae Moon 《ETRI Journal》2011,33(6):864-870
As an isotropic conductive adhesive, that is, a hybrid Cu paste composed of Cu powder, solder powder, and a fluxing resin system, has been quantitatively characterized. The mechanism of an electrical connection based on a novel concept of electrical conduction is experimentally characterized using an analysis of a differential scanning calorimeter and scanning electron microscope energy‐dispersive X‐ray spectroscopy. The oxide on the metal surface is sufficiently removed with an increase in temperature, and intermetallic compounds between the Cu and melted solder are simultaneously generated, leading to an electrical connection. The reliability of the hybrid Cu paste is experimentally identified and compared with existing Ag paste. As an example of a practical application, the hybrid Cu paste is used for LED packaging, and its electrical and thermal performances are compared with the commercialized Ag paste. In the present research, it is proved that, except the optical function, the electrical and thermal performances are similar to pre‐existing Ag paste. The hybrid Cu paste could be used as an isotropic conductive adhesive due to its low production cost. 相似文献
997.
998.
Design modeling of lithium-ion battery performance 总被引:1,自引:0,他引:1
A computer design modeling technique has been developed for lithium-ion batteries to assist in setting goals for cell components, assessing materials requirements, and evaluating thermal management strategies. In this study, the input data for the model included design criteria from Quallion, LLC for Gen-2 18650 cells, which were used to test the accuracy of the dimensional modeling. Performance measurements on these cells were done at the electrochemical analysis and diagnostics laboratory (EADL) at Argonne National Laboratory. The impedance and capacity related criteria were calculated from the EADL measurements. Five batteries were designed for which the number of windings around the cell core was increased for each succeeding battery to study the effect of this variable upon the dimensions, weight, and performance of the batteries. The lumped-parameter battery model values were calculated for these batteries from the laboratory results, with adjustments for the current collection resistance calculated for the individual batteries. 相似文献
999.
真空烧结工艺应用研究 总被引:1,自引:1,他引:0
在功率混合集成电路中,对功率芯片的组装要求热阻小和可靠性高,在这方面传统的芯片组装方法如银浆导电胶粘结或者回流焊接往往不能满足要求.介绍了功率芯片的一种新的组装工艺--真空烧结工艺,并对工艺实施过程中影响质量的因素以及解决办法进行了论述.通过试验和生产验证,证明真空烧结工艺解决了生产中存在的空洞较多和热阻较大等质量隐患... 相似文献
1000.
This work deals with the simulation of the fatigue crack growth (FCG) in bonded joints. In particular a cohesive damage model is implemented in the commercial software Abaqus, in order to take into account for the damage produced by fatigue loading. The crack growth rate is evaluated with different Paris-like power laws expressed in terms of strain energy release rate. The crack growth rate is then translated into a variation of the damage distribution over the cohesive zone setting an equivalence between the increment of crack length and the increment of damage. The model takes also into account mixed mode I/II conditions. In this work the validity of the model is tested by comparison with theoretical trends for conditions of pure mode I, pure mode II and mixed mode loading. In the case of mixed mode conditions, different models are implemented for the crack growth rate computation. The results of the model are in very good agreement with the expected trends, therefore the model is adequate to simulate the fatigue crack growth behaviour of bonded joint. 相似文献